1. Field of the Invention
This invention relates generally to the field of surgical devices and more particularly to resectoscopes and methods for their use.
2. Discussion of the Prior Art
A resectoscope is employed transurethrally to perform prostate and/or bladder surgery. This device has an elongate central working section provided with an outer sheath, usually made of stainless steel, which is inserted into the urethra. The outer sheath prevents the urethra from collapsing, while the working elements internally of the sheath are employed to cut away the desired tissue.
In U.S. Pat. No. 4,955,882 there is disclosed a resectoscope instrument embodying a laser for use in coagulating and removing prostate tissue. A cutting blade is provided in that instrument for cutting away tissue which had been coagulated by the laser. To that end, the instrument utilizes a forward directed laser to penetrate the tissue to be removed prior to cutting of that tissue. The instrument also includes means by which an irrigation fluid can be continuously supplied to and removed from the cutting site, so that the irrigation fluid, cut tissue and any debris are withdrawn through the instrument without the need to fully irrigate the site.
Some devices are now becoming available for effecting transurethral resection of the prostate by means of a laser. For example, Surgical Laser Technologies of Oaks, Pa. offers a "contact laser" which serves to vaporize the prostate in order to reduce bleeding and morbidity common with the traditional transurethral resection techniques.
When performing a prostate resection (or other tissue resection procedures, for that matter) it is desirable to be able to retrieve the removed tissue for analysis, e.g., histological examination. Thus, laser devices which do not includes any means for effecting the retrieval of laser tissue, particularly with the cellular architecture of that tissue substantially preserved, leave much to be desired from the standpoint of patient care. For example, the use of such devices leaves open the possibility of the failure to detect pathological conditions, e.g., malignant cells, in the removed tissue.
In U.S. Pat. No. 5,312,399, entitled Laser Resectoscope With Mechanical Cutting Means and Laser Coagulating Means, issued to Hakky and Hudson, which disclosure is incorporated by reference herein, there is disclosed a laser resectoscope and method of use for coagulating and causing hemostasis in tissue, e.g., prostate tissue, of a living being and for effecting the removal of the coagulated tissue, while preserving the cellular structure of the removed tissue for subsequent examination. That resectoscope comprises an elongated member having a distal end portion for introduction, e.g., through an introducer sheath, into the patient adjacent the tissue to be removed. Laser means are provided at the distal end portion of the elongated member for producing and directing a laser beam into the adjacent tissue for coagulating at least a portion of it. A rotatable cutting means is also located at the distal end portion of the apparatus for removing at least a portion of the coagulated tissue and for carrying that removed tissue to means for retrieving it. The rotatable cutting means operates in such a manner that the cellular structure of the coagulated tissue removed by the cutter is substantially preserved and hence suitable for viable histological examination.
The control of the operation of a surgical laser, particularly of a laser resectoscope, is of considerable importance, since the laser beam is capable of destroying both healthy and diseased tissues. Thus, heretobefore the use of surgical lasers has been typically restricted to physicians who have undergone intensive training in their use so that such physicians are able to judge tissue reaction to the laser beam. For example, a laser beam delivered to living tissue produces protein denaturation at 40 to 65.degree. C. At 65 to 85.degree. C., a laser beam produces tissue coagulation. Tissues whose temperatures are raised to a temperature of 95 to 400.degree. C., or more, vacuolizes, vaporizes or carbonizes, since a laser beam typically penetrates to a depth of between 0.5 to 4 millimeters below the surface of the tissue exposed to it.
Another concern in prostate and bladder resection is the removal of necrotic tissue and coagulated tissue which can avoid the use of a Foley catheter or shorten its use. The Foley catheter is used to divert the urine for many days from the prostate. This can cause irritation and possible infection.
Therefore, there exists a need for a laser resectoscope that efficiently removes tissue for diagnosis and necrotic tissue, and provides little risk regarding perforations of the prostatic urethra, rectum, or bladder.
There are many forms of laser applications. Laser energy can be applied using a fiber optic cable. The laser can be applied with the end tip of the fiber optic ("end lasing"). Here the laser beam fires from the tip of the fiber optic cable. The laser beam could also be deflected by a mirror so the beam will fire from the side of the fiber optic ("side firing"). In a new and novel laser application, Indigo Company in Cincinnati, a Johnson & Johnson Company, has devised an interstitial laser. The goal with an interstitial laser is to preserve the epithelial lining of the prostatic urethra and lase the core of the prostate surrounding a 2.5 centimeter segment of the fiber optic cable. In the interstitial laser, the end (5 centimeters) of the fiber optic is inserted inside the prostate (middle or the core of the prostate). Then laser energy is applied to the 2.5 centimeter tip of the fiber optic which is inside the prostatic core, and is uninsulated while the remaining fiber optic cable is insulated. Thus, when the laser energy is applied, the prostate tissue core surrounding the uninsulated 2.5 centimeter tip will be heated and thus be coagulated without damaging the overlying prostatic urethral lining. This interstitial laser application is meant to reduce the time the Foley catheter is left to divert the urine from the prostatic bed after the application of the laser.
Unfortunately, none of the above procedures remove coagulated or necrotic tissue. The lased prostate in all of the above is left to slough and pass with the urine over a period of 2 to 12 weeks. This can cause pain or discomfort during micturition. In addition, infection and scarring of the prostatic urethra mar the benefits of the laser.